1. Field of the Invention
The present disclosure relates to a reference voltage circuit. More particularly, the present disclosure relates to a reference voltage circuit having ultra-low power consumption and automatic on/off function; by detecting the offset between the reference voltage and the replicated voltage and transmitting the detection results back to the control logic circuit, the automatic on/off function of the reference voltage circuit is achieved.
2. Description of the Related Art
Nowadays, Microcontroller Unit (MCU) has been widely applied in many fields, and many designers in the Information Technology industry have embarked on the quest to design a MCU with low power consumption. For instance, when the MCU is applied in the intelligent water meter, it is a pressing issue to bring the power consumption of the MCU down in order to extend the battery life of the intelligent water meter.
An accurate reference voltage circuit is a very important element for the MCU; such reference voltage circuit should have characteristics including zero temperature coefficient, process drift resistance, not being affected by the variation in voltage source, etc. In addition to providing reference voltage to the Analog to Digital Converter (ADC) or the comparator, the reference voltage circuit serves as the reference for the power management circuit of the MCU. A high quality reference voltage circuit is the key to an excellent power management circuit, conventional reference voltage circuits with low power consumption design commonly found in the market are plagued with problems such as poor precision, excessive temperature coefficient, etc.
Besides, in a low power consumption system, the applied reference voltage (Vref or VBG) is usually generated by a bandgap reference circuit with low power consumption. Such bandgap reference circuit is of poor quality despite consuming less power. For instance, the bandgap reference circuit of poor quality might suffer from poor temperature compensation or the generated reference voltage might vary too much.